Field of the Invention
Embodiments of the present invention relate to a movable part tracking and treatment technique for treating an affected part of a patient displaced by respiration and other factors by emission of a beam.
Description of the Related Art
As a treatment technique for malignant tumors such as cancer, a technique using particle beams is attracting attention because of its excellent features such as high therapeutic effects, low side effects, and reduced load to the body.
When a particle beam enters a body of a patient, the beam loses its kinetic energy in the process of passing the body. Once the beam slows down to a certain prescribed rate, it suddenly stops and generates a large dose of radiation called a Bragg peak.
With the large dose of radiation generated at a pinpoint in this way, only cancer cells can be shot and killed while influence on healthy cells can be minimized.
Therefore, treatment apparatuses using a particle beam are required to accurately aim the beam to be emitted to the affected part so as to prevent normal tissues from being damaged.
Accordingly, in advance of emitting the beam, a position of the affected part is specified by X-ray observation and the like, and a position and an angle of a movable bed with the patient mounted thereon are appropriately adjusted, so that the affected part is accurately positioned within an emission range of the beam.
When the beam is emitted to an affected part present in an internal organ with motion (lung and the like), it is necessary to determine emission timing in consideration of periodic displacement caused by respiration and the like to ensure the accuracy of beam emission.
In such a case, a method as described below is conventionally adopted. That is, a gold marker or the like is embedded in a vicinity of an affected part, or the marker is pasted on a body surface of the patient, and movement of the marker is tracked with the aid of X-ray photography to identify the position of the affected part.